Question 65322
an airplane flies 1449 miles against the wind and 1539 miles with the wind in a total time of 5hours. the speed of the airplane in still air is 600mph. what is the speed of the wind ?
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Let "w" be the speed of the wind.
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Against the wind DATA:
distance=1449 miles ; rate= 600-w mph ; time= d/r = 1449/(600-w) hrs
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With the wind DATA:
distance=1539 miles ; rate=(600 + w) mph ; time= d/r = 1539/(600+w) hrs
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EQUATION:
time out + time back = 5 hrs
1449/(600-w) + 1539/(600+w) = 5 hrs
1449(600+w)+1539(600-w)=5(600^2-w^2)
1792800-90w=1800000-5w^2
5w^2-90w-7200=0
w^2-18w-1440=0
(w-48)(x+30)=0
w=48 mph (speed of the wind)
Cheers,
Stan H.